Biomass boilers are widely used in heating, power generation, and industrial production due to their diverse fuel sources and green, low-carbon characteristics. However, the high dust concentration in their flue gases requires effective dust removal treatment to prevent serious air pollution and adverse effects on downstream desulfurization and denitrification systems. Bag filter systems have become essential components in biomass boiler flue gas purification. This comprehensive guide covers system design optimization, operational management, common issues, and effective solutions.
The design air volume for dust collection systems should be based on the boiler's maximum flue gas volume with a 10-15% safety margin. The filtration velocity of bag filters is a critical design parameter. Excessive filtration velocity increases bag resistance and shortens service life, while insufficient velocity raises investment costs.
Recommended Parameters: Filtration velocity for biomass boiler bag filters should be maintained between 0.8-1.2 m/min, with adjustments based on fuel ash content and dust characteristics.
Biomass boiler flue gas temperatures typically range between 150-200°C and contain acidic gases and corrosive components. Filter bags should be made from high-temperature resistant, acid-alkali resistant, and corrosion-resistant materials.
Common Materials:
PPS (Polyphenylene Sulfide): Temperature resistance up to 190°C with excellent acid-alkali resistance
Aramid Needle Felt: Temperature resistance up to 200°C with high mechanical strength
PTFE Membrane Filter Media: Smooth surface prevents bag blinding and ensures high filtration precision
Proper airflow distribution prevents localized scouring and bag wear. Inlet designs should include flow guiding devices to ensure uniform gas distribution and avoid direct impact on bag bottoms. Outlets should provide sufficient cross-sectional area to prevent secondary dust re-entrainment from high-velocity airflow.
Design Specifications: Airflow distribution uniformity deviation should be controlled within ±15%, with inlet/outlet velocities maintained between 12-15 m/s.
Pulse jet pressure should be maintained at 0.5-0.7 MPa, with cleaning cycles automatically adjusted based on differential pressure. This ensures thorough bag cleaning while preventing bag fatigue from excessive pulsing.
Control Optimization: Advanced PLC control systems enable automatic monitoring of differential pressure, temperature, and fan operation status. Typical pulse intervals range from 2-5 minutes.
Biomass boiler flue gases often contain moisture and acidic components. Baghouse internal surfaces require anti-corrosion coatings with condensation prevention measures, while external insulation prevents low-temperature dew point corrosion.
Protection Measures: Shells should utilize epoxy resin anti-corrosion coatings with insulation thickness not less than 100mm, ensuring wall temperatures remain 10-15°C above dew point.
During startup, activate the induced draft fan first to establish negative pressure before igniting the boiler, preventing flue gas backflow. During shutdown, maintain fan operation to completely evacuate flue gases before turning off equipment, avoiding residual moisture corrosion.
Regularly monitor inlet-outlet differential pressure, typically maintained between 1200-1500 Pa. If pressure continuously increases, inspect for bag blinding, inadequate cleaning, or excessive hopper dust accumulation. Replace damaged bags promptly to prevent secondary dust emissions affecting downstream equipment.
Regularly discharge hopper dust to prevent excessive accumulation causing re-entrainment or blockages. Ensure conveying systems (screw conveyors, pneumatic conveying) operate properly to prevent dust backflow.
Biomass boiler dust possesses explosive characteristics. Install explosion venting or suppression systems to prevent fires from sparks entering bags. Consider spark arrestors or online temperature monitoring where necessary.
Root Causes: Bag surface condensation and blinding, pulse jet system malfunction, excessive hopper dust accumulation
Solutions: Inspect cleaning system, increase flue gas temperature or install membrane filter bags, clean hopper as needed
Root Causes: Uneven airflow distribution, excessive pulse pressure, inferior bag quality
Solutions: Inspect airflow distribution devices, adjust pulse parameters, optimize flow guidance, select premium quality bags
Root Causes: Discharge valve jamming, conveying system failure, high dust moisture content
Solutions: Inspect discharge valves and conveying system operation, clean and lubricate moving components regularly
Root Causes: Damaged insulation, flue gas temperature below dew point, failed anti-corrosion coating
Solutions: Inspect insulation integrity, adjust operating parameters to maintain wall temperature above dew point, install trace heating if necessary
Stable operation of bag filter systems depends not only on proper design but also on scientific operational management. During design phase, optimizing air velocity, selecting appropriate filter media, and improving airflow distribution can effectively extend bag life and reduce operational resistance. During operation, implementing differential pressure control, regular maintenance, hopper cleaning, and fire/explosion protection measures ensures long-term system safety and reliability.
| Design Optimization Measures | Operation & Maintenance Focus | Expected Outcomes |
|---|---|---|
| Optimal filtration velocity (0.8-1.2 m/min) | Differential pressure monitoring & adjustment | 30-50% extended bag life |
| PTFE membrane filter bag selection | Regular cleaning inspection | 99.9% filtration efficiency |
| Airflow distribution optimization | Regular hopper discharge | 40% reduced equipment wear |
| Comprehensive corrosion protection & insulation | Temperature & humidity monitoring | Corrosion prevention, extended equipment life |
The bag filter system serves as the primary barrier in biomass boiler flue gas purification, with its design quality and operational status directly impacting the efficiency and lifespan of downstream desulfurization and denitrification systems. Through scientific design optimization, meticulous operational management, and timely troubleshooting, operational costs can be significantly reduced while improving dust collection efficiency, thereby providing robust support for achieving ultra-low emissions and green production.
In practical engineering applications, companies in countries like Vietnam, Indonesia, and India are advised to develop customized dust collection solutions based on specific fuel characteristics, operating conditions, and emission requirements, ensuring systems operate efficiently, reliably, and economically.
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